Which is the most important part of a stereo system?


My system consists of a pair of B&W 630's, an old Denon 50 watt reciever (DRA-550) from the mid 80's, a Marantz CD5004 cd player, and now a Pro-ject Debut Carbon DC Turntable.  I'm pleased with the speakers and the cd player and while the Denon sounds good it has some issues and I want to upgrade.

I'm planning on returning the Pro-ject TT and getting a higher end TT.  I'm also looking into getting a new amp pre amp with a internal DAC.

Is the source the most important? The speakers? 

Please Help!
klimt
I will tend to you later, Mr. Smarty Pants 👖 If you don’t know just say you don’t know.
Which is the most important part of a stereo system?

There isn't one. As long as there is an audiophile around to argue about it nothing else matters.
Here are some examples of subconscious interaction with surroundings for your consideration. Comments accepted. 😬

The color blue for room walls is best for SQ.

The color green for the room ceiling is best for SQ.

The color white for any cable or power cord jacket is best for SQ.

Removing all CDs, LPs, DVDs or books in the room is best for the SQ.

Removing all cell phones from the room is best for the SQ.